The MUC5AC mucin plays an essential role in homeostasis of respiratory,
gastrointestinal and urogenital tracts under physiological conditions and fulfills various
important functions in human pathology. This chapter describes the molecular structure
of the MUC5AC gene and the mechanisms that regulate its activity. It analyzes the
biochemical and biophysical properties of the MUC5AC glycoprotein, its biosynthesis
and posttranslational modifications, as well as its expression in the respiratory,
gastrointestinal and male and female urogenital organs under physiological and
pathological conditions. The roles of the MUC5AC mucin in eye physiology and
pathology and in breast cancer are also discussed.
Keywords: MUC5AC, domain, biosynthesis, promoter, regulation, expression.